scholarly journals Tetragonal Distortion of a BaTiO3/Bi0.5Na0.5TiO3 Nanocomposite Responsible for Anomalous Piezoelectric and Ferroelectric Behaviors

ACS Omega ◽  
2020 ◽  
Vol 5 (36) ◽  
pp. 22800-22807 ◽  
Author(s):  
Wenxiong Zhang ◽  
Qi Feng ◽  
Eiji Hosono ◽  
Daisuke Asakura ◽  
Jun Miyawaki ◽  
...  
Keyword(s):  
Tetragonal Distortion

scholarly journals Site preference and tetragonal distortion in palladium-rich Heusler alloys

IUCrJ ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 218-225 ◽  
Author(s):  
Mengxin Wu ◽  
Yilin Han ◽  
A. Bouhemadou ◽  
Zhenxiang Cheng ◽  
R. Khenata ◽  
...  
Keyword(s):  
Density Of States ◽  
Phonon Dispersion ◽  
Heusler Alloys ◽  
Tetragonal Distortion ◽  
Site Preference ◽  
Peak Structure ◽  
Cubic System ◽  
The Difference ◽  
Full Heusler ◽  
Full Heusler Alloys

In this work, two kinds of competition between different Heusler structure types are considered, one is the competition between XA and L21 structures based on the cubic system of full-Heusler alloys, Pd2 YZ (Y = Co, Fe, Mn; Z = B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb). Most alloys prefer the L21 structure; that is, Pd atoms tend to occupy the a (0, 0, 0) and c (0.5, 0.5, 0.5) Wyckoff sites, the Y atom is generally located at site b (0.25, 0.25, 0.25), and the main group element Z has a preference for site d (0.75, 0.75, 0.75), meeting the well known site-preference rule. The difference between these two cubic structures in terms of their magnetic and electronic properties is illustrated further by their phonon dispersion and density-of-states curves. The second type of competition that was subjected to systematic study was the competitive mechanism between the L21 cubic system and its L10 tetragonal system. A series of potential tetragonal distortions in cubic full-Heusler alloys (Pd2 YZ) have been predicted in this work. The valley-and-peak structure at, or in the vicinity of, the Fermi level in both spin channels is mainly attributed to the tetragonal ground states according to the density-of-states analysis. ΔE M is defined as the difference between the most stable energy values of the cubic and tetragonal states; the larger the value, the easier the occurrence of tetragonal distortion, and the corresponding tetragonal structure is stable. Compared with the ΔE M values of classic Mn2-based tetragonal Heusler alloys, the ΔE M values of most Pd2CoZ alloys in this study indicate that they can overcome the energy barriers between cubic and tetragonal states, and possess possible tetragonal transformations. The uniform strain has also been taken into consideration to further investigate the tetragonal distortion of these alloys in detail. This work aims to provide guidance for researchers to further explore and study new magnetic functional tetragonal materials among the full-Heusler alloys.

CBED Investigations of Mesoscopic Semiconductor Structures

1999 ◽  
Vol 5 (S2) ◽  
pp. 208-209
Author(s):  
H. Lakner ◽  
F. Schulze-Kraasch ◽  
C. Mendorf ◽  
G. Brockt
Keyword(s):  
High Speed ◽  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Local Strain ◽  
Tetragonal Distortion ◽  
Strained Layers ◽  
Spatially Resolved ◽  
Relaxation Effects ◽  
Convergent Beam ◽  
Induced Defects

Ternary and quaternary heterostructures from III-V-semiconductors get more and more importance in the fabrication of high-speed/high frequency devices in telecommunication systems. One of the key parameters for the performance of such devices is the crystalline quality and especially the amount of tetragonal distortion in strained layers on a nanometer scale. Strain can cause problems for the growth of such layers like relaxation induced defects, especially for the case of a high value of lattice mismatch. However, strain and the associated influence on the band structure can be used consciously for the design of tailor-made heterostructures (band gap engineering). Therefore, the spatially resolved investigation of local crystal properties (tetragonal distortion or strain and strain relaxation) is a key tool for the characterization of strained layers.Convergent beam electron diffraction (CBED) patterns and convergent beam imaging (CBIM) can be used to evaluate informations on the local crystalline structure. E.g. the position of the High Order Laue Zone (HOLZ) lines in the CBED patterns is sensitive to the local strain and therefore can be used to determine strain and relaxation effects in heterostructures quantitatively. But in practice the applicability of CBED is often limited by a lack of ultimate spatial resolution and/or of sensitivity.

scholarly journals Phase Stability and Magnetic Properties of Mn3Z (Z = Al, Ga, In, Tl, Ge, Sn, Pb) Heusler Alloys

2019 ◽  
Vol 9 (5) ◽  
pp. 964 ◽  
Author(s):  
Haopeng Zhang ◽  
Wenbin Liu ◽  
Tingting Lin ◽  
Wenhong Wang ◽  
Guodong Liu
Keyword(s):  
Magnetic Properties ◽  
Structural Stability ◽  
Phase Stability ◽  
First Principles ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Atomic Radius ◽  
Tetragonal Distortion ◽  
Stable Phase ◽  
First Principles Calculations

The structural stability and magnetic properties of the cubic and tetragonal phases of Mn3Z (Z = Ga, In, Tl, Ge, Sn, Pb) Heusler alloys are studied by using first-principles calculations. It is found that with the increasing of the atomic radius of Z atom, the more stable phase varies from the cubic to the tetragonal structure. With increasing tetragonal distortion, the magnetic moments of Mn (A/C and B) atoms change in a regular way, which can be traced back to the change of the relative distance and the covalent hybridization between the atoms.

High Sensitivity Convergent Beam Electron Diffraction for the Determination of the Tetragonal Distortion of Epitaxial Films

1999 ◽  
Vol 589 ◽  
Author(s):  
C. Schuer ◽  
M. Leicht ◽  
T. Marek ◽  
H.P. Strunk
Keyword(s):  
Electron Diffraction ◽  
High Sensitivity ◽  
Diffraction Theory ◽  
Gaas Layer ◽  
Convergent Beam Electron Diffraction ◽  
Epitaxial Films ◽  
Tetragonal Distortion ◽  
Beam Electron ◽  
Convergent Beam

AbstractWe have optimized the sensitivity of convergent beam electron diffraction (CBED) by orienting the specimen such that the central (000) diffraction disc shows a pattern of defect lines that are most sensitive to tetragonal distortion. We compare the position of these lines in the experimentally obtained patterns with results from computer simulations, which need to be based on dynamical diffraction theory. In both experimental and simulated patterns the positions of the defect lines are determined by applying a Hough transformation. As a result of this optimized approach, we can measure the tetragonal distortion of a low temperature grown GaAs layer as low as 0.04%.

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